Washing machine and washing control method of the same

ABSTRACT

A washing machine and a washing control method of the same that squeeze detergent water from the laundry, heat the squeezed detergent water, and resupply the heated detergent water, thereby performing heated washing using a minimized amount of water. The washing machine includes a water tub, a rotary drum mounted in the water tub to receive laundry, and a circulation unit to supply water from the water tub into the rotary drum. The washing control method includes detecting an amount of a load according to a weight of the laundry, supplying an amount of water set according to the detected amount of load, supplying the water in the water tub into the rotary drum through the circulation unit to wet the laundry, separating the water from the laundry by rotating the rotary drum, and heating the separated water and resupplying the heated water into the rotary drum through the circulation unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.2007-19123, filed on Feb. 26, 2007 in the Korean Intellectual PropertyOffice, the disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field

The present invention relates to a washing machine and a washing controlmethod of the same to perform heated washing using a small amount ofwater.

2. Description of the Related Art

Generally, a washing machine (normally, a drum type washing machine) isa machine, including a water tub to receive water (wash water or rinsewater) and a cylindrical rotary drum rotatably mounted in the water tubto receive laundry, that washes the laundry by lifting and dropping thelaundry in the rotary drum along the inner surface of the rotary drumduring the rotation of the rotary drum.

This washing machine detects the weight of laundry (the amount of aload) to decide the amount of wash water according to a user's selectionof a washing course, supplies water having an amount sufficient to wetthe laundry and detergent into the water tub according to the decidedamount of wash water, heats the water and the detergent supplied intothe water tub using a heater disposed between the water tub and therotary drum, when heated washing is to be performed, and performs awashing operation while detergent water (water+detergent), thetemperature of which is increased by the heater, is forwarded to thelaundry, and the laundry is dropped by the rotation of the rotary drum.

However, it is necessary to fill a space defined between the water tuband the rotary drum with water to perform the washing. As a result, alarge amount of water is used, and therefore, a large amount of energyis required to increase the temperature of the water. Also, as waterconsumption increases, a large amount of detergent is used to performhigh-concentration washing.

Furthermore, when the amount of water supplied is small, the amount ofwater gathered in the water tub is also small, because the water isabsorbed in the laundry during the wetting of the laundry. As a result,the heater is exposed, and therefore, it is not possible to performheated washing. Although the water is gathered in the water tub, onlythe gathered water is heated, and therefore, the heated water does notreach the center of the laundry. Consequently, the temperature of thelaundry is not uniformly distributed, whereby the washing efficiency isvariable.

SUMMARY

Therefore, it is an aspect of the invention to provide a washing machineand a washing control method of the same to rotate a rotary drum, at theminimum RPM at which laundry is spin-dried, to squeeze out water fromthe laundry, heating the squeezed water, and resupplying the heatedwater to the laundry, thereby performing heated washing using aminimized amount of water.

In another aspect of the invention, a washing machine and a washingcontrol method of the same supply water during the squeezing out ofwater from laundry by the rotation of a rotary drum at the minimum RPMat which the laundry is spin-dried, and heat the squeezed water when thesqueezed water is below a heater safety water level, thereby securingthe safety of heated washing.

In a further aspect of the invention, a washing machine and a washingcontrol method of the same increase the temperature of water to a targettemperature during the squeezing out of water from laundry, by therotation of a rotary drum at the minimum RPM at which the laundry isspin-dried, and heat the squeezed water, and uniformly distribute theheated water throughout the laundry, thereby accomplishing uniformwashing efficiency.

In accordance with one aspect of the present invention, a washingcontrol method of a washing machine that includes a water tub, a rotarydrum mounted in the water tub to receive laundry, and a circulation unitto supply water from the water tub into the rotary drum, the washingcontrol method includes detecting the amount of the load according tothe weight of the laundry, supplying an amount of water set according tothe detected amount of the load into the water tub, supplying the waterin the water tub into the rotary drum through the circulation unit towet the laundry, separating the water absorbed in the laundry from thelaundry by rotating the rotary drum, and heating the separated water andresupplying the heated water into the rotary drum through thecirculation unit.

Generally, the set amount of water is the minimum water supply amountset based on the detected amount of the load.

Typically, the water supplied into the water tub is detergent waterincluding detergent and wash water mixed with each other.

Generally, the operation of separating the water absorbed in the laundryfrom the laundry includes squeezing out the detergent water absorbed inthe laundry from the laundry by rotating the rotary drum at the minimumRPM at which the laundry may be spin-dried.

Typically, the minimum RPM is approximately 50 to 300 RPM.

Generally, the washing control method further includes detecting thewater level of the water before heating the water. The detected waterlevel is compared with a predetermined water level, and, when thedetected water level is below the predetermined water level, water issupplied into the water tub.

Typically, the predetermined water level is a heater safety water levelat which the water may be heated.

Generally, the washing control method further includes detecting thetemperature of the water. The detected temperature is compared with apredetermined target temperature, and, when the detected temperature isbelow the target temperature, the water is heated until the temperatureof the water reaches the target temperature.

Typically, the operation of heating the separated water includesactivating a washing heater to heat the water until the temperature ofthe water reaches the target temperature, and, when the detectedtemperature has reached the target temperature, deactivating the washingheater to maintain the water resupplied into the rotary drum at theoptimum temperature.

In another aspect, a washing machine includes a water tub to receivewater, a rotary drum mounted in the water tub to receive laundry, acirculation unit to supply the water in the water tub into the rotarydrum, a water supply unit to control the supply of water, a washingheater to heat water, and a control unit to control the water supplyunit to supply water into the water tub, control the circulation unit tosupply the water in the water tub into the rotary drum such that thelaundry is wetted by the water, control the washing heater to heat thewater in the water tub after the water absorbed in the laundry isseparated from the laundry by the rotation of the rotary drum, andcontrol the heated water to be resupplied into the rotary drum such thatwashing is performed using the heated water.

Generally, the control unit detects the amount of the load according tothe weight of the laundry and controls the water supply unit to supplyan amount of water set according to the detected amount of the load intothe water tub.

Typically, the control unit rotates the rotary drum at the minimum RPMat which the laundry may be spin-dried to squeeze out the detergentwater absorbed in the laundry from the laundry.

Generally, the washing machine further includes a water level detectionunit to detect the water level of the water. The control unit comparesthe water level detected by the water level detection unit with apredetermined water level before heating the water, and, when thedetected water level is below the predetermined water level, controlsthe water supply unit to supply water into the water tub.

Typically, the washing machine further includes a temperature detectionunit to detect the temperature of the water. The control unit comparesthe temperature detected by the temperature detection unit with apredetermined target temperature, activating the washing heater untilthe temperature of the water reaches the target temperature when thedetected temperature is below the target temperature, and deactivatingthe washing heater to maintain the water resupplied into the rotary drumat the optimum temperature when the detected temperature has reached thetarget temperature.

Additional aspects and/or advantages of the invention will be set forthin part in the description which follows and, in part, will be obviousfrom the description, or may be learned by practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the invention will becomeapparent and more readily appreciated from the following description ofthe embodiments, taken in conjunction with the accompanying drawings, ofwhich:

FIG. 1 is a sectional view illustrating the supply of water to laundryin a washing machine according to an embodiment of the presentinvention;

FIG. 2 is a sectional view illustrating the squeezing out of water fromthe laundry supply of water to laundry in the washing machine accordingto an embodiment of the present invention;

FIG. 3 is a perspective view of a rotary drum applied to an embodimentof the present invention;

FIG. 4 is a sectional view of the rotary drum;

FIG. 5 is a control block diagram of the washing machine according to anembodiment of the present invention; and

FIGS. 6A and 6B are flow charts illustrating a washing control method ofthe washing machine according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Reference will now be made in detail to the embodiment of the presentinvention, examples of which are illustrated in the accompanyingdrawings, wherein like reference numerals refer to like elementsthroughout. The embodiment is described below to explain the presentinvention by referring to the figures.

FIG. 1 is a sectional view illustrating the supply of water to laundryin a washing machine according to an embodiment of the presentinvention, and FIG. 2 is a sectional view illustrating the squeezing outof water from the laundry in accordance with an embodiment of thepresent invention.

Referring to FIGS. 1 and 2, the washing machine includes a drum-typewater tub 11 mounted in a machine body 10 to receive water (wash wateror rinse water) and a cylindrical rotary drum 12 rotatably mounted inthe water tub 11.

The water tub 11 is mounted at a predetermined angle α to theinstallation surface of the washing machine such that a front part 11 a,having an inlet 11 b formed therein, is located at a higher positionthan a rear part 11 c. The rotary drum 12 is mounted in the water tub 11in the same inclination angle as the water tub 11 such that a front part12 a, having an inlet 12 b formed therein, is located at a higherposition than a rear part 12 c.

Outside the rear part 11 c of the water tub 11 is mounted a drive unit,such as a motor 15, to rotate a rotary shaft 13 connected to the rotarydrum 12 such that washing, rinsing, and spin-drying operations areperformed. The motor 15 includes a stator 15 a fixed to the rear part 11c of the water tub 11, a rotor 15 b rotatably disposed around the stator15 a, and a rotary plate 15 c connected between the rotor 15 b and therotary shaft 13.

At the inside bottom of the water tub 11 is mounted a washing heater 16to heat water (specifically, detergent water) supplied into the watertub 11. For the installation of the washing heater 16, a heaterreceiving part 17 is formed in the bottom of the water tub 11. Theheater receiving part 17 protrudes downward such that a predeterminedamount of water is gathered in the heater receiving part 17 while thewashing heater 16 is received in the heater receiving part 17.Consequently, the washing heater 16 is immersed in the water gathered inthe heater receiving part 17. Since the washing heater 16 is received inthe heater receiving part 17, the rotary drum 12 may be rotated withoutinterference between the rotary drum 12 and the washing heater 16.

In the front of the machine body 10 is formed an inlet 18 bcorresponding to the inlet 12 b of the rotary drum 12 and the inlet 11 bof the water tub 11 such that laundry may be put into or taken out fromthe rotary drum 12. At the machine body 10, adjacent to the inlet 18 b,is mounted a door 18 to open and close the inlet 18 b. Between the inlet10 b of the machine body 10 and the inlet 11 b of the water tub 11 ismounted a cylindrical diaphragm 11 d to prevent the leakage of washwater.

Above the water tub 11 are mounted a detergent supply unit 19 to supplydetergent and a water supply unit 20 to supply water (wash water orrinse water).

The detergent supply unit 19 has several partitioned spaces. Thedetergent supply unit 19 is mounted at the front side of the machinebody 10 such that a user easily puts detergent and rinse in therespective partitioned spaces. The detergent supply unit 19 includes apreliminary washing detergent box to store detergent used forpreliminary washing, a main washing detergent box to store detergentused for main washing, and a rinse box to store rinse used for rinsing.The details of the detergent supply unit 19 are disclosed in KoreanPatent Application No. 2003-0011317, which has been filed in the name ofthe applicant of the present application. Of course, other well-knowntechnologies may be applied to the detergent supply unit 19.

The water supply unit 20 includes a first water supply pipe 22 connectedbetween an external water supply pipe 21, through which water (washwater or rinse water) is supplied into the water tub 11, and thedetergent supply unit 19, a second water supply pipe 23 connectedbetween the detergent supply unit 19 and the water tub 11, and a watersupply valve 24 mounted on the first water supply pipe 22 to control thesupply of water. Consequently, water is supplied into the water tub 11via the detergent supply unit 19 such that detergent is supplied intothe water tub 11 together with the water.

The washing machine further includes a drainage unit 30 to drain thewater in the water tub 11 and a circulation unit 40 to supply the water,heated by the washing heater 16, in the water tub 11 into the rotarydrum 12. The drainage unit 30 includes a first drainage pipe 31connected to a drainage port 17 a formed at the heater receiving part 17in the bottom of the water tub 11 to guide the water in the water tub 11to the outside, a drainage pump 32 mounted on the first drainage pipe31, and a second drainage pipe 33 connected to the outlet of thedrainage pump 32. The circulation unit 40 includes a flow channelswitching valve 41 mounted on the second drainage pipe 33, a circulationpipe 42 extending from the flow channel switching valve 41 to the inlet12 b of the rotary drum 12, and an injection nozzle 43 mounted at theoutlet of the circulation pipe 42. The flow channel switching valve 41serves to switch flow channels such that water from the outlet of thedrainage pump 32 is drained to the outside or flows to the circulationpipe 42. The flow channel switching valve 41 may be an electricthree-way valve. The injection nozzle 43 is mounted adjacent to theinlet 12 b of the rotary drum 12 such that the injection nozzle 43injects water into the rotary drum 12 through the inlet 12 b of therotary drum 12.

Consequently, when the drainage pump 32 is operated while the flowchannel switching valve 41 is operated such that water flows to thecirculation pipe 42, water in the bottom of the water tub 11 is injectedinto the rotary drum 12 through the first drainage pipe 31 and thecirculation pipe 42. Also, when the drainage pump 32 is operated whilethe flow channel switching valve 41 is operated such that water flows tothe second drainage pipe 33, the water in the water tub 11 is drained tothe outside.

FIG. 3 is a perspective view of a rotary drum applied to an embodimentof the present invention, and FIG. 4 is a sectional view of the rotarydrum.

Referring to FIGS. 3 and 4, the rotary drum 12 is mounted such that arotation axis A of the rotary drum 12 is at a predetermined angle α tothe installation surface of the washing machine while the front part 12a, having the inlet 12 b formed therein, is directed forward. In thiscase, the rotary shaft 13, coupled to the center of the rear part 12 cof the rotary drum 12, is rotatably supported at the rear central partof the water tub 11 such that the rotary drum 12 may be rotated in thewater tub 11.

The reason why the rotation axis A of the rotary drum 12 is at thepredetermined angle α to the installation surface of the washing machineis that, when water is supplied into the rotary drum 12, a predeterminedamount of water necessary for washing and rinsing is gathered in therotary drum 12 such that laundry is wetted by the water.

In the front part 12 a of the rotary drum 12 are formed a plurality ofspin-drying holes 12 d. Inside the rotary drum 12 are mounted aplurality of lifters 14 to raise and drop laundry in the rotary drum 12during the rotation of the rotary drum 12. The reason why thecircumference of the rotary drum 12 is at a predetermined angle β to therotation axis A of the rotary drum 12 and the holes 12 d are formedalong the edge of the front part 12 a is to guide water, moving in theradial direction of the rotary drum 12 due to a centrifugal force causedwhen the rotary drum 12 is rotated at the minimum RPM at which laundrymay be spin-dried, to the holes 12 d of the front part 12 a along theincline such that the water is drained out of the rotary drum 12. Foreffective drainage, the tilt angle β at the circumference of the rotarydrum 12 is generally 0.5 degrees or more.

FIG. 5 is a control block diagram of the washing machine according to anembodiment of the present invention. In addition to the components shownin FIGS. 1 and 2, the washing machine further includes a signal inputunit 50, a water level detection unit 52, a temperature detection unit54, a control unit 56, and a drive unit 58.

The signal input unit 50 inputs operation information, such as a washingcourse, a washing temperature, spin-drying RPM, and the addition ofrinsing, which are selected by a user, to the control unit 56. The waterlevel detection unit 52 detects the water level of water supplied intothe water tub 11, and the temperature detection unit 54 detects thetemperature of water supplied into the water tub 11.

The control unit 56 is a microcomputer to control the washing machinebased on the operation information inputted from the signal input unit50. The control unit 56 stores the amount of wash water, motor RPM andoperation rate (motor on-off time), and washing time set according tothe amount of the load (the weight of laundry) in the selected washingcourse.

For heated washing, therefore, the control unit 56 supplies the water(specifically, detergent water) in the water tub 11 into the rotary drum12 through the circulation unit 40 to wet laundry after the supply of apredetermined amount of wash water, rotates the rotary drum 12, at theminimum RPM at which the laundry may be spin-dried, to squeeze out waterfrom the laundry, and detects the water level of the squeezed water. Thecontrol unit 56 controls the driving of the motor 15, the washing heater16, the water supply unit 20, and the circulation unit 40 such that,when the detected water level is below a predetermined heater safetywater level, water is supplied through the water supply unit 20 untilthe water level reaches the heater safety water level, and, when thedetected water level reaches the predetermined heater safety waterlevel, water is heated by activating the washing heater 16 until thetemperature of the water reaches a target temperature, and the heatedwater is resupplied into the rotary drum 12.

The drive unit 58 drives the motor 15, the washing heater 16, the watersupply valve 24, the drainage pump 32, and the flow channel switchingvalve 41 according to a drive control signal of the control unit 56.

Hereinafter, the operation of the washing machine with the above-statedconstruction and a washing control method of the washing machine will bedescribed.

FIGS. 6A and 6B are flow charts illustrating a washing control method ofthe washing machine according to an embodiment of the present invention.

First, when a user puts laundry in the rotary drum 12 and selectsoperation information, such as a washing course, washing temperature,spin-drying RPM, and the addition of rinsing, based on the kinds of thelaundry, the operation information selected by the user is inputted tothe control unit 56 through the signal input unit 54.

Subsequently, the control unit 56 determines whether the power is on sothat a washing operation is performed based on the operation informationinputted from the signal input unit 54 (S100).

When the power is on, the control unit 56 detects the amount of the load(the weight of laundry) put in the rotary drum 12 (S102), and sets theminimum amount of wash water, motor operation rate (motor on-off time),and washing time for each washing course based on the detected amount ofthe load (S104).

Subsequently, the control unit 56 controls the water supply unit 20 tosupply the minimum amount of wash water set for each washing coursebased on the amount of the load. As a result, the water supply valve 24is opened, and water (wash water) flows through the water supply pipes21 and 22, the detergent supply unit 19, and the second water supplypipe 23, whereby detergent water, (water+detergent) is supplied into thewater tub 11 (S106).

During the supply of detergent water for washing, the water leveldetection unit 52 detects the water level of the detergent watersupplied into the water tub 11 to determine whether the detected waterlevel is at a predetermined first water level (a water level decidedaccording to the set amount of wash water) (S108).

When the detected water level has not reached the predetermined firstwater level, the control unit 56 controls water to be continuouslysupplied into the water tub 11 until the water level reaches the firstwater level. When the detected water level reaches the predeterminedfirst water level, the control unit 56 closes the water supply valve 24such that the water supply is interrupted (S110).

After the interruption of the water supply, the control unit 56 controlsthe circulation unit 40 such that laundry is wetted by the detergentwater supplied into the water tub 11. As a result, the flow channelswitching valve 41 of the circulation unit 50 is operated such that theoutlet of the drainage pump 32 communicates with the circulation pipe42. As the drainage pump 32 is operated, the detergent water in thebottom of the water tub 11 is supplied into the rotary drum 12 throughthe drainage pipe 31 and the circulation pipe 42 (S112). At this time,the detergent water, supplied into the rotary drum 12, is injected tothe laundry through the injection nozzle 43 such that the laundry isuniformly wetted by the detergent water.

After a wetting operation to supply the detergent water in the water tub11 into the rotary drum 12 through the circulation unit 40 is performedfor a predetermined period of time (time decided according to the amountof the load; approximately 4 minutes), the control unit 56 rotates therotary drum 12 at a predetermined first RPM (the minimum RPM at whichlaundry may be spin-dried; approximately 50 to 300 RPM) for apredetermined period of time (approximately 1 minute) to secure a heatersafety water level at which the detergent water may be heated.

As the rotary drum 12 is rotated at the first RPM, detergent waterabsorbed in the laundry is separated from the laundry and is introducedinto the water tub 11 through the holes 12 d formed in the front part 12a of the rotary drum 12. The water level of the detergent water gatheredin the water tub 11 is detected (S114).

The control unit 56 determines whether the water level of the detergentwater gathered in the water tub 11 has reached a predetermined secondwater level (a heater safety water level necessary for heated washing; awater level at which the washing heater is immersed in the detergentwater) (S116). When the water level of the detergent water does notreach a level of the second water level, the control unit 56 controlsthe water supply unit 20 to resupply water into the water tub 11 untilthe water level of the detergent water reaches the second water level(S118).

When it is determined at S116 that the water level of the detergentwater gathered in the water tub 11 has reached the second water level,which means that the heater safety water level for heating is secured,the control unit 56 controls the washing heater to heat the detergentwater gathered in the water tub 11 (S120).

At this time, the control unit 56 controls the circulation unit 40 to beoperated such that the laundry is heated by the heated detergent water.As a result, the heated detergent water in the water tub 11 is suppliedinto the rotary drum 12 through the drainage pipe 31 and the circulationpipe 42 (S122). The detergent water, supplied into the rotary drum 12,is injected to the laundry through the injection nozzle 43 with theresult that the laundry is uniformly heated.

Also, the control unit 56 detects the temperature of the heateddetergent water by utilizing the temperature detection unit 54 (S124),and determines whether the temperature of the detergent water hasreached a predetermined target temperature (a default value based onwashing temperature set by a user or a basic default value) (S126).

When it is determined at S126 that the temperature of the detergentwater has not yet reached the target temperature, the procedure returnsto S120 to activate the washing heater 16 until the temperature of thedetergent water has reached the target temperature.

When it is determined at S126, on the other hand, that the temperatureof the detergent water has reached the target temperature, the controlunit 56 turns the washing heater 16 off (i.e., deactivates the washingheater) (S128), and continuously supplies the detergent water, heated tothe target temperature, into the rotary drum 12 through the circulationunit 40 to uniformly heat the entire laundry (S130).

At this time, the control unit 56 controls the motor 15 to be driven,such that the rotary drum 12 is operated at a predetermined second RPM(washing RPM) and operation rate, to perform heated washing thataccomplishes uniform washing efficiency using the minimum amount ofwater (S132).

As the heated washing is performed, the temperature of the detergentwater gradually decreases. At this time, the temperature detection unit54 detects the temperature of the detergent water and inputs thedetected temperature of the detergent water to the control unit 56.

The control unit 56 determines whether the detected temperature of thedetergent water is below a predetermined first temperature (atemperature of the detergent water at which the washing heater isredriven) (S136). When the detected temperature of the detergent wateris below the first temperature, the control unit 56 controls the rotarydrum 12 to be rotated at a predetermined third RPM (approximately 150RPM) for a predetermined period of time (approximately 1 minute) suchthat the detergent water is separated from the laundry (S138), and theprocedure returns to S120 to heat the detergent water to the targettemperature.

When it is determined at S136 that the detected temperature of thedetergent water is not below the first temperature, which means that thetemperature of the detergent water is suitable for heated washing, thecontrol unit 56 determines whether a washing time set according to theamount of the load has elapsed (S140). When the washing time has notelapsed, the procedure returns to S130 to perform a washing operationthat washes the laundry using the heated detergent water.

When it is determined at S140 that the washing time has elapsed, thecontrol unit 56 performs a subsequent rinsing and spin-drying operationset according to the amount of the load (S142).

As is apparent from the above description, the washing machine accordingto embodiments of the present invention and the washing control methodof the same have the effect of rotating the rotary drum at the minimumRPM at which laundry may be spin-dried, after the supply of water, tosqueeze out water from the laundry, heating the squeezed water, andresupplying the heated water to the laundry, thereby performing heatedwashing using a minimized amount of water, and therefore, accomplishingwater and power saving.

Furthermore, the washing machine according to embodiments of the presentinvention and the washing control method of the same have the effect ofsupplying water, during the squeezing out of water from laundry, by therotation of the rotary drum at the minimum RPM at which the laundry maybe spin-dried, and heating the squeezed water, when the squeezed wateris below the heater safety water level, thereby securing the safety ofheated washing. Also, the washing machine according to embodiments ofthe present invention and the washing control method of the same havethe effect of increasing the temperature of water to the targettemperature during the squeezing out of water from laundry by therotation of the rotary drum at the minimum RPM at which the laundry maybe spin-dried, and heating the squeezed water when the temperature ofthe squeezed water has fallen below the heater safety water level, anduniformly distributing the heated water throughout the laundry, therebyaccomplishing uniform washing efficiency.

Although a few embodiments of the present invention have been shown anddescribed, it would be appreciated by those skilled in the art thatchanges may be made in this embodiment without departing from theprinciples and spirit of the invention, the scope of which is defined inthe claims and their equivalents.

1. A washing control method of a washing machine including a water tub,a rotary drum mounted in the water tub to receive laundry, and acirculation unit to supply water from the water tub into the rotarydrum, the washing control method comprising: detecting an amount of aload according to a weight of the laundry; supplying an amount of waterset according to the detected amount of the load into the water tub;supplying the water in the water tub into the rotary drum through thecirculation unit to wet the laundry; separating the water, absorbed inthe laundry, from the laundry by rotating the rotary drum; and heatingthe separated water and resupplying the heated water into the rotarydrum through the circulation unit.
 2. The washing control methodaccording to claim 1, wherein the set amount of water is a minimum watersupply amount set based on the detected amount of the load.
 3. Thewashing control method according to claim 1, wherein the water suppliedinto the water tub is detergent water including detergent and wash watermixed with each other.
 4. The washing control method according to claim3, wherein the separating the water, absorbed in the laundry, from thelaundry includes squeezing out the detergent water absorbed in thelaundry from the laundry by rotating the rotary drum at a minimum RPM atwhich the laundry is spin-dried.
 5. The washing control method accordingto claim 4, wherein the minimum RPM is approximately 50 to 300 RPM. 6.The washing control method according to claim 1, further comprising:detecting a water level of the water before heating the water, whereinthe detected water level is compared with a predetermined water level,and, when the detected water level is below the predetermined waterlevel, water is supplied into the water tub.
 7. The washing controlmethod according to claim 6, wherein the predetermined water level is aheater safety water level at which the water is heated.
 8. The washingcontrol method according to claim 1, further comprising: detecting atemperature of the water, wherein the detected temperature is comparedwith a predetermined target temperature, and, when the detectedtemperature is below the target temperature, the water is heated untilthe temperature of the water reaches the target temperature.
 9. Thewashing control method according to claim 8, wherein the heating theseparated water includes activating a washing heater until thetemperature of the water reaches the target temperature, and, when thedetected temperature has reached the target temperature, deactivatingthe washing heater to maintain the water resupplied into the rotary drumat an optimum temperature.
 10. A washing machine comprising: a water tubto receive water; a rotary drum mounted in the water tub to receivelaundry; a circulation unit to supply the water in the water tub intothe rotary drum; a water supply unit to control the supply of water; awashing heater to heat water; and a control unit to control the watersupply unit to supply water into the water tub, control the circulationunit to supply the water in the water tub into the rotary drum such thatthe laundry is wetted by the water, control the washing heater to heatthe water in the water tub after the water, absorbed in the laundry, isseparated from the laundry by the rotation of the rotary drum, andcontrol the heated water to be resupplied into the rotary drum such thatwashing is performed using the heated water.
 11. The washing machineaccording to claim 10, wherein the control unit detects an amount of aload according to a weight of the laundry and controls the water supplyunit to supply an amount of water set according to the detected amountof the load into the water tub.
 12. The washing machine according toclaim 11, wherein the set amount of water is a minimum water supplyamount set based on the detected amount of the load.
 13. The washingmachine according to claim 10, wherein the water supplied into the watertub is detergent water including detergent and wash water mixed witheach other.
 14. The washing machine according to claim 13, wherein thecontrol unit rotates the rotary drum, at a minimum RPM at which thelaundry is spin-dried to squeeze out the detergent water absorbed in thelaundry from the laundry.
 15. The washing machine according to claim 14,wherein the minimum RPM is approximately 50 to 300 RPM.
 16. The washingmachine according to claim 10, further comprising: a water leveldetection unit to detect a water level of the water, wherein the controlunit compares the water level detected by the water level detection unitwith a predetermined water level before heating the water, and, when thedetected water level is below the predetermined water level, controlsthe water supply unit to supply water into the water tub.
 17. Thewashing machine according to claim 16, wherein the predetermined waterlevel is a heater safety water level at which the water is heated. 18.The washing machine according to claim 10, further comprising: atemperature detection unit to detect a temperature of the water, whereinthe control unit compares the temperature detected by the temperaturedetection unit with a predetermined target temperature, and activatesthe washing heater until the temperature of the water reaches the targettemperature when the detected temperature is below the targettemperature.
 19. The washing machine according to claim 18, wherein theheating the separated water includes when the detected temperature hasreached the target temperature, deactivating the washing heater tomaintain the water resupplied into the rotary drum at an optimumtemperature.
 20. A controller for a washing machine, comprising: meansfor detecting an amount of a load according to a weight of laundry;means for causing an amount of water set according to the detectedamount of the load to be supplied into the water tub; means for causingthe water in the water tub to be supplied into the rotary drum throughthe circulation unit to wet the laundry; means for causing the rotarydrum to rotate and separate the water absorbed in the laundry from thelaundry; and means for causing the separated water to be heated and,after heating to a predetermined temperature, to be resupplied into therotary drum through the circulation unit.